Refractory Hypotension After Spinal Anesthesia in a Patient on an SGLT2 Inhibitor
A 68-year-old man (BMI 31, eGFR 42 mL/min/1.73 m², HbA1c 8.4%) on empagliflozin, metformin, lisinopril, and carvedilol presents for an open inguinal hernia repair under spinal anesthesia. He has been NPO since midnight. On arrival at 07:30 his glucose is 132 mg/dL and he is euvolemic by history but admits to 'cutting back' on fluids after reading about fasting. Spinal anesthesia is placed to T8. Twenty minutes later his blood pressure is 78/44 mmHg with a heart rate of 58 bpm. He receives 500 mL of crystalloid, 10 mg ephedrine, then 100 mcg phenylephrine, with only transient improvement (BP 84/48). He becomes mildly confused and reports nausea.
1. List the differential for this patient's persistent hypotension beyond simple sympathectomy, and explain which elements of the setup most raise concern for each.
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Beyond the expected sympathectomy from a T8 block, consider:
- Hypovolemia from SGLT2-inhibitor-related osmotic diuresis plus self-restricted intake. Empagliflozin causes ongoing glycosuria regardless of fasting status; combined with reduced oral intake since midnight, this produces a subtle but real volume deficit that a standard 500 mL bolus will not correct. The 'cutting back on fluids' history and eGFR 42 are the key clues.
- Euglycemic diabetic ketoacidosis (euDKA). SGLT2 inhibitors can precipitate euDKA perioperatively, especially with fasting, surgery, and reduced carbohydrate intake. Glucose of 132 mg/dL does not exclude it; the mild confusion and nausea are red flags. This is the most dangerous item on the list.
- Carvedilol blunting the compensatory tachycardic response - HR of 58 during hypotension is inappropriately slow and limits the utility of ephedrine.
- High neuraxial block - recheck the sensory level; a level drifting above T4 would explain bradycardia plus hypotension (Bezold–Jarisch–like reflex).
- Anaphylaxis, myocardial ischemia, or sepsis - less likely given the timing and absence of rash/wheal, but ischemia must be excluded with ECG given the cardiac risk profile.
2. The surgeon is ready and asks whether to proceed. Outline your immediate management and the workup you would obtain before continuing.
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Immediate management:
- Recheck the sensory level. If it is above T4, treat as a high block (position, fluids, vasopressors, consider epinephrine if severe bradycardia).
- Give a larger fluid challenge (e.g., 500–1000 mL balanced crystalloid) rather than continued small aliquots, given likely volume depletion.
- Switch vasopressor strategy: with a beta-blocked patient and bradycardia, phenylephrine alone may worsen bradycardia; use a norepinephrine infusion (or ephedrine with caution) to provide both alpha and beta support. Consider glycopyrrolate if HR remains <50 with hypotension.
- Check a point-of-care glucose, blood gas, and beta-hydroxybutyrate/ketones. A normal glucose with elevated ketones and anion gap confirms euDKA; this changes management to insulin + dextrose infusion and makes proceeding unsafe.
- 12-lead ECG and troponin if any chest pain, dyspnea, or persistent instability.
Decision: If euDKA is confirmed or the patient remains unstable after fluid and vasopressor optimization, defer the case. A hernia repair is elective; proceeding with an unresolved metabolic or hemodynamic problem exposes the patient to avoidable harm. If the picture is purely volume depletion and responds to a proper fluid challenge with stable vitals, proceeding with heightened vigilance is reasonable.
3. What would you do differently for this patient's next anesthetics, and what perioperative guidance applies to SGLT2 inhibitors?
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- Hold the SGLT2 inhibitor for at least 3–4 days before elective surgery (longer for ertugliflozin per some guidance), consistent with FDA and multi-society recommendations to reduce euDKA risk.
- Preoperative hydration counseling: explicitly tell the patient not to restrict fluids beyond the standard fasting window; clear liquids up to 2 hours preop are appropriate and protective.
- Avoid prolonged fasting and consider a carbohydrate-containing clear liquid preop.
- Intraoperative glucose and ketone surveillance in diabetic patients on these agents, especially with fasting, acute illness, or major surgery.
- Anticipate volume depletion - these patients behave like a mild diuretic; plan for generous balanced crystalloid and have norepinephrine available.
- Recognize that beta blockade (carvedilol) blunts reflex tachycardia, so choose vasopressors that support both tone and rate rather than relying on ephedrine alone.